The Hunt for New Pulsars with the Green Bank Telescope Hunt for New Pulsars with the Green Bank...

IAU XXVII General AssemblyAugust 20, 2012

Symposium 291Neutron Stars and Pulsars

The Hunt for New Pulsars with the Green Bank Telescope

Ryan LynchPostdoctoral Fellow

McGill University



What we'll talk about...

● Two most recent large-area GBT pulsar surveys – the 350 MHz Drift Scan Survey and the Green Bank North Celestial Cap Survey● Primary science goals● Progress so far● Highlights● Future work

● A brief overview of some targeted pulsar searches



● Anne Archibald (McGill)

● Aaron Berndsen (UBC)

● Jason Boyles (WVU)

● Fernando Cardoso (WVU)

● Angus Cherry (UBC)

● Jason Hessels (ASTRON)

● Rick Jenet (UTB)

● David Kaplan (UWM)

● Vicky Kaspi (McGill)

● Chen Karako (McGill)

● Vlad Kondratiev (ASTRON)

● Duncan Lorimer (WVU)

● Joeri van Leeuwen (ASTRON)

● Erik Madsen (UBC)

● Maura McLaughlin (WVU)

● Christie McPhee (UBC)

● Chris Pankow (UWM)

● Tim Pennucci (UVA)

● Scott Ransom (NRAO)

● Mallory Roberts (Eureka)

● Xavier Siemens (UWM)

● Ingrid Stairs (UBC)

● Kevin Stovall (UTB)

● ARCC (UTB/UWM)



First, some motivation

● We keep finding cool new pulsars whenever we look, so keep looking! ● High precision MSPs for PTAs● Gravitational laboratories (Kramer et al. 2006; Freire et

al. 2012)● Massive pulsars (e.g. Demorest et al. 2010)● Radio magnetars (Camilo et al. 2006,2007; Levin et al.

2010)● And many, many more...

● Different surveys can be complementary



The importance of the GBT

● Largest fully steerable telescope in the world

● Can see parts of the sky that Arecibo and Parkes can't

● Relatively little RFI

● Several excellent low-noise receivers

● State-of-the art pulsar back-end

Image credits: Wikipedia & NRAO



The GBT Drift Scan survey

● Primary science goal: find high precision MSPs and exotic pulsars (young pulsars, RRATs, etc)

● Completed between May and August 2007 during GBT track repair shutdown

● Access to -7.7° < δ < 38.4° and -20.7° < δ < 38.4°

Image credit: NRAO




● Centered at 350 MHz with 50 MHz bandwidth● Most data recorded with 2048 channels

● Data analyzed in 140-s sections with 50% overlap

● 10347 sq deg, totaling 1491 hrs of observing time and 134 TB● 2800 sq deg reserved for Pulsar Search Collaboratory

(Rosen et al. 2010)

● Data analysis now complete: 31 new pulsars including 7 MSPs (P < 10 ms)



GBT Drift Scan Highlights

● J0348+0432 is a 39-ms recycled pulsars in a 2.4-hr orbit (Lynch et al. in prep)● Spectroscopic follow-up of the companion reveals a

0.17 Msun white dwarf (Antoniadis et al. in prep)● Predicted to be a strong emitter of dipolar GWs by

scalar-tensor theories of gravity

● Ongoing Arecibo timing will provide one of the most stringent tests ever of these alternative gravity theories (Antoniadis et al.)



J0348+0432 Pb-dot prediction

Courtesy of N. Wex




● J0337+1715 is a 2.7-ms MSP in a hierarchical triple (Ransom et al. in prep)

● Inner companion is a WD on 1.6 day orbit

● Outer companion on a 327 day orbit

● Already is proving to be a fantastic test-bed for 3-body dynamical theory

Courtesy of S. Ransom




● J2222-0137 (Boyles et al. in prep) is a 33-ms recycled pulsar with a > 1.1 Msun companion● Look for Shapiro delay measurement results soon

● J1923+2515 and J0931+1906 are 2 MSPs already included in NANOGrav and IPTA timing

● J1023+0038 (Archibald et al. 2009): The “missing link” pulsar

● 34 RRAT candidates discovered by Chen Karako (see tomorrow's talk)



The GBNCC survey

● Science goals similar to Drift Scan, but with particular emphasis on high declinations● More wide-separation baselines for pulsar timing arrays● Probe pulsar and RRAT populations in less well studied

part of the Galaxy● Data taking began in 2009 and is ongoing

● Stage I covered δ > 38° and is now complete

● Stage II pushing south and will cover entire sky visible from the GBT



The GBNCC survey

● Centered at 350 MHz using newer GUPPI back-end● 100 MHz bandwidth with 4096 channels● 120-s pointed integrations

● Will use 2030 hrs and amass ~360 TB when completed● Early processing by Kevin Stovall at UTB● Most processing now at McGill using 2048 cores on the

Guillimin supercomputer

● Preliminary results: 50 new pulsars including 9 MSPs



The GBNCC survey



J0636+51P = 2.86 msDM = 11.1 pc/cc

J0645+51P = 8.85 msDM = 18.2 pc/cc

Included in NANOGrav & IPTA

J0741+66P = 2.88 msDM = 15 pc/cc

J1122+78P = 4.2 msDM = 11.2 pc/cc

J1710+49P = 3.2 msDM = 7.1 pc/cc

J1649+80P = 2.0 msDM = 31 pc/cc



GBNCC Highlights

● J1816+4510 is a binary MSP in an 8.7-hr orbit around a > 0.16 Msun companion (Kaplan et al. 2012)● Detected with Fermi and has UV/optical counterpart

Kaplan et al. (2012)



GBNCC Highlights

● J0510+38 is a 76-ms pulsars with b=1° (possible young pulsar?)

● J0737+69 is a 6.8-s pulsar● Only 6 radio pulsars with longer periods (3 are

RRATs)● J0636+51 is a 2.9-ms MSP in a 1.5 hr orbit

● Lower limit on companion's density is 2x diamond planet (Bailes et al. 2012)



GBNCC Highlights

● 4 intermediate-period pulsars with |b| > 10° (possible relativistic binaries?)

● Several pulsars and MSPs with DM-distances < 1 kpc → promising targets for multi-wavelength follow-up



Targeted surveys: Globular Clusters

● The GBT has been amazing for finding GC pulsars● The most promising GCs have been deeply searched

as part of several projects (Ransom et al. 2005; Freire et al. 2008; Lynch et al. 2011a/b, 2012, Stairs et al. In prep)

● These included the fastest rotator (Hessels et al. 2006), potentially super-massive pulsars (Freire et al. 2008), and a potential double neutron star system (Lynch et al. 2012)



Targeted Surveys: Globular Clusters

Courtesy of S. Ransom



Targeted surveys: Fermi sources

● Fermi has revolutionized the search for field MSPs● 45 MSPs have been discovered by targeting bright,

unidentified Fermi sources (see Ray et al. 2012)● 26 of these have been discovered using the GBT



Summary and Conclusions

● There are still lots of really cool pulsars to discover!● Pulsar-BH binary, planet systems, bridges between

magnetars and pulsars, RRATs, massive pulsars...● The GBT is one of the best instruments in the world for

finding new pulsars

● The most recent GBT surveys have combined to discover 81 new pulsars (12 MSPs)

● The ongoing GBNCC survey promises to keep increasing this number by a lot (so stay tuned)

The Hunt for New Pulsars with the Green Bank Telescope Hunt for New Pulsars with the Green Bank...

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